The present invention relates to the use of Co-phthalocyanine complexes and a light-absorbing compound in the information layer of recordable optical data media, which information layer is recordable using light, optical data media, and a process for their production.
The singly recordable compact disc (CD-R) has recently been experiencing an enormous growth in quantity. The light-absorbing compound of the information layer represents a substantial component of the optical data medium and has to meet correspondingly high and varied requirements. Not infrequently, the preparation of such compounds is correspondingly complicated (cf. WO-A 00/09522).
It is accordingly an object of the invention to provide a phthalocyanine dye that is simple to synthesize and meets the high requirements (such as light stability, advantageous signal/noise ratio, high recording sensitivity, damage-free application of the substrate material, and the like) for use as a light-absorbing compound in the information layer of a singly recordable optical data medium (chiefly CD-R).
It has surprisingly been found that Co-phthalocyanine complexes are suitable for this purpose.
The invention relates to an optical data medium containing a transparent substrate, on the surface of which are applied at least one recordable information layer that is recordable using light and optionally a reflection layer, optionally one or more intermediate layers, and/or optionally a protective layer, wherein the information layer contains, as a light-absorbing compound, at least one Co-phthalocyanine complex of the formula (I) 
in which
CoPc represents cobalt(III) phthalocyanine,
L1 and L2 are axial, coordinately bonded ligands of the cobalt central atom and represent an amine of the formula NR0R1R2 or represent an isonitrile of the formula 
xe2x80x83in which
R0, R1, and R2 independently of one another, represent hydrogen, alkyl, cycloalkyl, alkenyl, aryl, or hetaryl or two of the radicals R0 to R2, together with the N atom to which they are bonded, form a hydrogenated, partly hydrogenated, quasiaromatic, or aromatic ring (preferably a 5- to 7-membered ring) that optionally contains further heteroatoms (particularly from the group consisting of N, O, and/or S),
R represents alkyl, cycloalkyl, alkenyl, aryl, or hetaryl, and
R3, R 4, R5, and R6 are substituents of phthalocyanine and, independently of one another, represent halogen, cyano, alkyl, aryl, alkylamino, dialkylamino, alkoxy, alkylthio, aryloxy, arylthio, SO3H, SO2NR7R8, CO2R12, CONR7R8, NHxe2x80x94COR12, or a radical xe2x80x94(B)mxe2x80x94D in which
B denotes a bridge member from the group consisting of a direct bond, CH2, CO, CH(alkyl), C(alkyl)2, NH, S, O, or xe2x80x94CHxe2x95x90CHxe2x80x94, such that (B)m denotes a chemically expedient sequence of bridge members B where m is 1 to 10 (preferably 1, 2, 3, or 4),
D represents the monovalent radical of a redox system of the formula 
xe2x80x83or 
xe2x80x83or represents a metallocenyl radical or metallocenylcarbonyl radical in which titanium, manganese, iron, ruthenium, or osmium is suitable as a metal center, in which
X1 and X2, independently of one another, represent NRxe2x80x2Rxe2x80x3, ORxe2x80x3, or SRxe2x80x3,
Y1 represents NRxe2x80x2, O, or S, Y2 represents NRxe2x80x2,
n represents 1 to 10, and
Rxe2x80x2 and Rxe2x80x3, independently of one another, represent hydrogen, alkyl, cycloalkyl, aryl, or hetaryl, or form a direct bond or a bridge to one of the C atoms of the 
xe2x80x83chain,
w, x, y, and z, independently of one another, represent 0 to 12 and w+x+y+z are 12,
R7 and R8, independently of one another, represent alkylamino, hydroxy alkylamino, dialkylamino, bishydroxyalkylamino, or arylamino, or R7 and R8, together with the N atom to which they are bonded, form a heterocyclic 5-, 6-, or 7-membered ring, optionally with participation of further heteroatoms (particularly from the group consisting of O, N, and S, such that NR7R8 represents in particular pyrrolidino, piperidino, or morpholino),
R12 represents alkyl, aryl, hetaryl, or hydrogen, and
Anxe2x88x92 represents an anion, particularly halide, C1- to C20-alkylCOOxe2x88x92, formate, oxalate, lactate, glycolate, citrate, CH3OSO3xe2x88x92, NH2SO3xe2x88x92, CH3SO3xe2x88x92, xc2xd SO42xe2x88x92, or ⅓ PO43xe2x88x92.
The Co-phthalocyanine complex of the formula (I) may also be present in the form of formula (Ia) 
in which
CoPc, L2, the radicals R3-R6, and the indices w, x, y, and z have the same meaning as in formula (I), and
R11 is a covalently bonded radical of the cobalt central atom and derived from the primary or secondary amine or from the isonitrile in the meaning of L1 (i.e., xe2x80x94NR1R2, R1 and R2 having the above-mentioned meaning, or 
For the sake of simplicity, however, the following statements all relate to the compounds of the formula (I) and, of course, also apply in the same manner to the formula (Ia).
Preferred heterocyclic amine ligands in the meaning of L1 and L2 are morpholine, piperidine, piperazine, pyridine, 2,2-bipyridine, 4,4-bipyridine, pyridazine, pyrimidine, pyrazine, imidazole, benzimidazole, isoxazole, benzisoxazole, oxazole, benzoxazole, thiazole, benzothiazole, quinoline, pyrrole, indole, and 3,3-dimethylindole, which are coordinated in each case at the nitrogen atom with the cobalt atom.
The alkyl, alkoxy, aryl, and heterocyclic radicals can optionally carry further radicals, such as alkyl, halogen, hydroxyl, hydroxyalkyl, amino, alkylamino, dialkylamino, nitro, cyano, COxe2x80x94NH2, alkoxy, alkoxycarbonyl, morpholino, piperidino, pyrrolidino, pyrrolidono, trialkylsilyl, trialkylsiloxy, or phenyl. The alkyl and alkoxy radicals may be saturated, unsaturated, straight-chain, or branched, the alkyl radicals may be partly halogenated or perhalogenated, and the alkyl and alkoxy radicals can be ethoxylated or propoxylated or silylated. Neighboring alkyl and/or alkoxy radicals on aryl or heterocyclic radicals can together form a three- or four-membered bridge.
Preferred compounds of the formula (I) are those in which the following are true for the radicals R0 to R8 and R, Rxe2x80x2, Rxe2x80x3, and R12 and for the ligands L1 and L2:
substituents having the designation xe2x80x9calkylxe2x80x9d preferably denote C1-C16-alkyl (particularly C1-C6-alkyl), which are optionally substituted by halogen (such as chlorine, bromine, or fluorine), hydroxyl, cyano, and/or C1-C6-alkoxy;
substituents having the designation xe2x80x9calkoxyxe2x80x9d preferably denote C1-C16-alkoxy (particularly C1-C6-alkoxy), which are optionally substituted by halogen (such as chlorine, bromine, or fluorine), hydroxyl, cyano, and/or C1-C6-alkyl;
substituents having the designation xe2x80x9ccycloalkylxe2x80x9d preferably denote C4-C8-cycloalkyl (particularly C5-C6-cycloalkyl), which are optionally substituted by halogen (such as chlorine, bromine, or fluorine), hydroxyl, cyano, and/or C1-C6-alkyl;
substituents having the designation xe2x80x9calkenylxe2x80x9d preferably denote C6-C8-alkenyl, which are optionally substituted by halogen (such as chlorine, bromine, or fluorine), hydroxyl, cyano, and/or C1-C6-alkyl, particularly allyl;
substituents having the meaning xe2x80x9chetarylxe2x80x9d preferably represent heterocyclic radicals having 5- to 7-membered rings, which preferably contain heteroatoms selected from the group consisting of N, S, and/or O and are optionally fused to aromatic rings or optionally carry further substituents (for example halogen, hydroxyl, cyano, and/or alkyl), the following being particularly preferred: pyridyl, furyl, thienyl, oxazolyl, thiazolyl, imidazolyl, quinolyl, benzoxazolyl, benzothiazolyl, and benzimidazolyl, and
the substituents having the designation xe2x80x9carylxe2x80x9d preferably denote C6-C10-aryl (particularly phenyl or naphthyl), which are optionally substituted by halogen (such as F or Cl), hydroxyl, C1-C6-alkyl, C1-C6-alkoxy, NO2, and/or CN.
Preferred Co-phthalocyanine complexes of the formula (I) are those in which
L1 and L2, independently of one another, represent ammonia, methyl-amine, ethylamine, ethanolamine, propylamine, isopropylamine, butylamine, isobutylamine, tert-butylamine, pentylamine tert-amyl-amine, benzylamine methylphenylhexylamine, aminopropylamine, aminoethylamine, 3-dimethylaminopropylamine, 3-diethylamino-propylamine, diethylaminoethylamine, dibutylaminopropylamine, morpholinopropylamine, piperidinopropylamine, pyrrolidinopropyl-amine, pyrrolidonopropylamine, 3-(methyl-hydroxyethylamino)pro-pylamine, methoxyethylamine, ethoxyethylamine, methoxypropyl-amine, ethoxypropylamine, methoxyethoxypropylamine, 3-(2-ethyl-hexyloxy)propylamine, isopropyloxyisopropylamine, dimethylamine, diethylamine, diethanolamine, dipropylamine, diisopropylamine, dibutylamine, diisobutylamine, di-tert-butylamine, dipentylamine, di-tert-amylamine, bis(2-ethylhexyl)amine, bis(aminoethyl)amine, bis(aminopropyl)amine, bis(dimethylaminopropyl)amine, bis(diethyl-aminopropyl)amine, bis(diethylaminoethyl)amine, bis(dibutylamino-propyl)amine, di(morpholinopropyl)amine, di(piperidinopropyl)-amine, di(pyrrolidinopropyl)amine, di(pyrrolidonopropyl)amine, bis(3-(methyl-hydroxyethylamino)propyl)amine, dimethoxyethyl-amine, diethoxyethylamine, dimethoxypropylamine, diethoxypropyl-amine, di(methoxyethoxyethyl)amine, di(methoxyethoxypropyl)-amine, bis(3-(2-ethylhexyloxy)propyl)amine, di(isopropoxyiso-propyl)amine, tripropylamine, tri(methoxyethoxyethyl)amine, tri(methoxyethoxypropyl)amine, diethylaminoethylpiperazine, dipropylaminoethylpiperazine, morpholine, piperidine, piperazine, pyridylamine, 2-thiazolylamine, 2-benzothiazolylamine, 2-benzox-azolylamine, 3-iminoisoindoleninylamine, pyridine, propylpyridine, butylpyridine, 2,2-bipyridine, 4,4-bipyridine, pyridazine, pyrimidine, pyrazine, imidazole, benzimidazole, isoxazole, benzisoxazole, oxazole, benzoxazole, thiazole, benzothiazole, quinoline, pyrrole, indole, 3,3-dimethylindole, aminopyridine, aniline, p-toluidine, p-tert-butylaniline, p-anisidine, isopropylaniline, butoxyaniline, or naphthyl-amine,
or
L1 and L2, independently of one another, represent methylisonitrile, ethyl-isonitrile, ethanolisonitrile, propylisonitrile, isopropylisonitrile, butyl-isonitrile, isobutylisonitrile, tert-butylisonitrile, pentylisonitrile, tert-amylisonitrile, benzylisonitrile, methylphenylhexylisonitrile, amino-propylisonitrile, aminoethylisonitrile, 3-dimethylaminopropylisonitrile, 3-diethylaminopropylisonitrile, diethylaminoethylisonitrile, dibutyl-aminopropylisonitrile, morpholinopropylisonitrile, piperidinopropyl-isonitrile, pyrrolidinopropylisonitrile, pyrrolidonopropylisonitrile, 3-(methyl-hydroxyethylamino)propylisonitrile, methoxyethylisonitrile, ethoxyethyl isonitrile, methoxypropylisonitrile, ethoxypropylisonitrile, methoxyethoxypropylisonitrile, 3-(2-ethylhexyloxy)propylisonitrile, isopropyloxyisopropylisonitrile, dimethylisonitrile, diethylisonitrile, diethanolisonitrile, dipropylisonitrile, diisopropylisonitrile, dibutyl-isonitrile, diisobutylisonitrile, di-tert-butylisonitrile, dipentylisonitrile, di-tert-amylisonitrile, bis(2-ethylhexyl)isonitrile, bis(aminoethyl)iso-nitrile, bis(aminopropyl)isonitrile, bis(dimethylaminopropyl)isonitrile, bis(diethylaminopropyl)isonitrile, bis(diethylaminoethyl)isonitrile, bis(dibutylaminopropyl)isonitrile, di(morpholinopropyl)isonitrile, di(piperidinopropyl)isonitrile, di(pyrrolidinopropyl)isonitrile, di(pyrrolidonopropyl)isonitrile, bis(3-(methyl-hydroxyethylamino)propyl)-isonitrile, dimethoxyethylisonitrile, diethoxyethylisonitrile, dimethoxy-propylisonitrile, diethoxypropylisonitrile, di(methoxyethoxyethyl)-isonitrile, di(methoxyethoxypropyl)isonitrile, bis(3-(2-ethylhexyloxy)-propyl)isonitrile, di(isopropyloxyisopropyl)isonitrile, tripropylisonitrile, tri(methoxyethoxyethyl)isonitrile, tri(methoxyethoxypropyl)isonitrile, pyridylisonitrile, 2-thiazolylisonitrile, 2-benzothiazolylisonitrile, 2-benzoxazolylisonitrile, 3-iminoisoindoleninylisonitrile, phenyliso-nitrile, p-tert-butylphenylisonitrile, p-methoxyphenylisonitrile, iso-propylphenylisonitrile, butoxyphenylisonitrile, or naphthylisonitrile,
R3, R4, R5, and R6, independently of one another, represent chlorine, fluorine, bromine, iodine, cyano, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, tert-amyl, hydroxyethyl, 3-dimethyl-aminopropyl, 3-diethylaminopropyl, phenyl, p-tert-butylphenyl, p-methoxyphenyl, isopropylphenyl, trifluoromethylphenyl, naphthyl, methylamino, ethylamino, propylamino, isopropylamine, butylamino, isobutylamino, tert-butylamino, pentylamino, tert-amylamino, benzylamino, methylphenylhexylamino, hydroxyethylamino, amino-propylamino, aminoethylamino, 3-dimethylaminopropylamino, 3-diethyla minopropylamino, diethylaminoethylamino, dibutylamino-propylamino, morpholinopropylamino, piperidinopropylamino, pyrrolidinopropylamino, pyrrolidonopropylamino, 3-(methyl-hydroxy-ethylamino)propylamino, methoxyethylamino, ethoxyethylamino, methoxypropylamino, ethoxypropylamino, methoxyethoxypropyl-amino, 3-(2-ethylhexyloxy)propylamino, isopropoxypropylamino, dimethylamino, diethylamino, diethanolamino, dipropylamino, diisopropylamino, dibutylamino, diisobutylamino, di-tert-butylamino, dipentylamino, di-tert-amylamino, bis(2-ethylhexyl)amino, bis-(aminopropyl)amino, bis(aminoethyl)amino, bis(3-dimethylamino-propyl)amino, bis(3-diethylaminopropyl)amino, bis(diethylamino-ethyl)amino, bis(dibutylaminopropyl)amino, di(morpholinopropyl)-amino, di(piperidinopropyl)amino, di(pyrrolidinopropyl)amino, di(pyrrolidonopropyl)amino, bis(3-(methyl-hydroxyethylamino)-propyl)amino, dimethoxyethylamino, diethoxyethylamino, dimethoxypropylamino, diethoxypropylamino, di(methoxyethoxy-ethyl)amino, di(methoxyethoxypropyl)amino, bis(3-(2-ethylhexyl-oxy)propyl)amino, di(isopropoxyisopropyi)amino, methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tert-butoxy, pentyloxy, tert-amyloxy, methoxyethoxy, ethoxyethoxy, methoxypropoxy, ethoxy-propoxy, methoxyethoxypropoxy, 3-(2-ethylhexyloxy)propoxy, methylthio, ethylthio, propylthio, isopropylthio, butylthio, isobutylthio, tert-butylthio, pentylthio, tert-amylthio, phenyl, methoxyphenyl, trifluoromethylphenyl, naphthyl, CO2R12, CONR7R8, NHxe2x80x94COR12, SO3H, or SO2NR7R8 or represent a radical of the formula 
in which
(B)m represents 
xe2x80x83the asterisk (*) indicating the link to the 5-membered ring,
M represents an Mn or Fe cation,
w, x, y, and z, independently of one another, represent 0 to 8 and w+x+y+z are 12,
Anxe2x88x92 represents chloride, bromide, fluoride, C1- to C20-alkylCOOxe2x88x92, formate, oxalate, lactate, glycolate, citrate, CH3OSO3xe2x88x92, NH2SO3xe2x88x92, CH3SO3xe2x88x92, xc2xd SO42xe2x88x92, or ⅓ PO43xe2x88x92,
NR7R8 represents amino, methylamino, ethylamino, propylamino, iso-propylamino, butylamino, isobutylamino, tert-butylamino, pentyl-amino, tert-amylamino, benzylamino, methylphenylhexylamino, 2-ethyl-1-hexylamino, hydroxyethylamino, aminopropylamino, amino-ethylamino, 3-dimethylaminopropylamino, 3-diethylaminopropyl-amino, morpholinopropylamino, piperidinopropylamino, pyrrolidinopropylamino, pyrrolidonopropylamino, 3-(methyl-hydroxyethyl-amino)propylamino, methoxyethylamino, ethoxyethylamino, methoxypropylamino, ethoxypropylamino, methoxyethoxypropyl-amino, 3-(2-ethylhexyloxy)propylamino, isopropyloxyisopropyl-amino, dimethylamino, diethylamino, dipropylamino, diisopropyl-amino, dibutylamino, diisobutylamino, di-tert-butylamino, dipentyl-amino, di-tert-amylamino, bis(2-ethylhexyl)amino, dihydroxyethyl-amino, bis(aminopropyl)amino, bis(aminoethyl)amino, bis(3-di-methylaminopropyl)amino, bis(3-diethylaminopropyl)amino, di(morpholinopropyl)amino, di(piperidinopropyl)amino, di(pyrrolidinopropyl)amino, di(pyrrolidonopropyl)amino, bis(3-(methyl-hydroxy-ethylamino)propyl)amino, dimethoxyethylamino, diethoxyethyl-amino, dimethoxypropylamino, diethoxypropylamino, di(methoxy-ethoxypropyl)amino, bis(3-(2-ethylhexyloxy)propyl)amino, di(iso-propyloxyisopropyl)amino, anilino, p-toluidino, p-tert-butylanilino, p-anisidino, isopropylanilino, or naphtylamino or NR7R8 represents pyrrolidino, piperidino, piperazino, or morpholino,
R12 represents hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl tert-butyl, pentyl, tert-amyl, phenyl, p-tert-butylphenyl, p-methoxy-phenyl, isopropylphenyl, p-trifluoromethylphenyl, cyanophenyl, naphthyl, 4-pyridyl, 2-pyridyl, 2-quinolinyl, 2-pyrrolyi, or 2-indolyl,
it being possible for the alkyl, alkoxy, aryl, and heterocyclic radicals optionally to carry further radicals, such as alkyl, halogen, hydroxyl, hydroxyalkyl, amino, alkylamino, dialkylamino, nitro, cyano, COxe2x80x94NH2, alkoxy, alkoxycarbonyl, morpholino, piperidino, pyrrolidino, pyrrolidono, trialkylsilyl, trialkylsiloxy, or phenyl, for the alkyl and/or alkoxy radicals to be saturated, unsaturated, straight-chain, or branched, for the alkyl radicals to be partially halogenated or perhalogenated, for the alkyl and/or alkoxy radicals to be ethoxylated or propoxylated or silylated, and for neighboring alkyl and/or alkoxy radicals on aryl or heterocyclic radicals together to form a three- or four-membered bridge.
In the context of this invention, redox systems are understood as meaning in particular the redox systems described in Angew. Chem. 1978, page 927, and in Topics of Current Chemistry, Vol. 92, page 1 (1980).
p-Phenylenediamines, phenothiazines, dihydrophenazines, bipyridinium salts (viologens), and quinodimethanes are preferred.
Particularly preferred Co complexes of the formula (I) are those that correspond to the formula (Ib) 
in which
halogen represents chlorine, bromine, or fluorine,
alkoxy represents C1-C6-alkoxy,
R7 and R8, independently of one another, have the above-mentioned meanings,
An"sgr", CoPc, and R2 likewise have the above-mentioned meanings.
The invention also relates to compounds of the formula (Ic) 
in which
halogen represents chlorine, bromine, or fluorine,
alkoxy represents C1-C6-alkoxy that is optionally substituted,
R7 and R8, independently of one another, have the above meanings, and
the other substituents have the above-mentioned meanings.
The invention also relates to a process for the preparation of compounds of the formula (Ic) by oxidizing a Co-phthalocyanine substituted by sulfonamido groups of the formula SO2NR7R8, in which R7 and R8 have the above-mentioned meanings, and optionally by halogen and/or alkoxy, and then reacting the resultant oxidized intermediate with amines L1 and L2 (which are independently NH2R2).
The preparation is preferably carried out starting from a Co-phthalocyanine optionally substituted by halogen and/or alkoxy by sulfochlorination with chlorosulfonic acid and thionyl chloride at 50-130xc2x0 C. and reaction of the resultant intermediate with the corresponding amine in water at pH 8-12 at from room temperature to 100xc2x0 C. to give the amide. The subsequent introduction of the axial amine substituents is preferably effected in a known manner under oxidizing conditions, e.g., chlorine or air, preferably air, and, when using air, in the presence of excess amine (cf. Example 13). When using chlorine, the oxidation is carried out first and the amine is then added.
In addition to the compound of the formula (I), the information layer that is recordable using light particularly preferably additionally contains, as light-absorbing compounds, at least one other optionally substituted phthalocyanine with or without a central atom.
A suitable central atom is, for example, one from the group consisting of Si, Zn, Al, Cu, Pd, Pt, Au, and Ag, particularly Cu and Pd.
For example, the sulfonamido-substituted Cu-phthalocyanines disclosed in DE-A 19 925 712 are particularly preferred. Particularly preferred are those of the formula (II) 
in which
CuPc represents a copper phthalocyanine radical,
A represents an optionally substituted straight-chain or branched C2-C6-alkylene, such as, for example, ethylene, propylene, butylene, pentylene, or hexylene,
R9 and R10, independently of one another, represent hydrogen or optionally substituted straight-chain or branched C1-C6-alkyl, such as, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, particularly substituted C1-C6-hydroxyalkyl and unsubstituted C1-C6-alkyl,
or R9 and R10, together with the N atom to which they are bonded, form a heterocyclic 5- or 6-membered ring that optionally contains a further heteroatom(e.g., S, N, or O),
x represents 2.0 to 4.0,
y represents 0 to 1.5, and
the sum of x and y is 2.0 to 4.0(preferably 2.5 to 4.0).
Particularly preferred components of the mixture are those of the formula (II) that correspond to the formula (IIa)
CuPc-[SO2NHxe2x80x94CH2CH2CH2N(CH2)3]xe2x80x83xe2x80x83(IIa), 
In which CuPc denotes copper phthalocyanine.
The sulfonamido- or amido-substituted phthalocyanines, as disclosed, for example, in EP-A 519,395, are suitable as further preferred additional light-absorbing compounds.
For mixtures of different light-absorbing compounds, the proportion of the compounds of the formula (I) is preferably 10 to 90% thereof. A mixture of the formulas (I) and (II) in a weight ratio of 10:90 to 90:10, preferably 20:80 to 80:20, particularly preferably of 40:60 to 60:40, is particularly preferred.
The information layer can also contain binders, wetting agents, stabilizers, diluents, and sensitizers and further components in addition to the light-absorbing compound.
The substrates can be produced from optically transparent plastics that, if necessary, have been provided with a surface treatment. Preferred plastics are polycarbonates and polyacrylates, as well as polycycloolefins or polyolefins.
The reflection layer can be produced from any metals or metal alloys that are usually used for recordable optical data media. Suitable metals or metal alloys can be applied by vapor deposition and sputtering and contain, for example, gold, silver, copper, aluminum, and alloys thereof with one another or with other metals.
The possible protective layer over the reflection layer may consist of UV-curable acrylates.
A possible intermediate layer that protects the reflection layer, for example, from oxidation, may likewise be present.
The invention furthermore relates to a process for the production of the optical data media according to the invention whereby the information layer that is recordable using light is applied to a transparent substrate by coating with at least one Co-phthalocyanine complex of the formula (I), optionally in combination with suitable binders, additives, and solvents, and is further optionally provided with a reflection layer, optionally further intermediate layers and optionally a protective layer.
The coating of the substrate with the light-absorbing compound of the formula (I) is optionally effected in combination with further dyes, binders, and/or solvents, preferably by spin coating.
For the coating, the light-absorbing compound of the formula (I) is preferably dissolved, with or without additives, in a suitable solvent or solvent mixture, so that the compound of the formula (I) accounts for 100% or less, for example, 10 to 20 parts by weight per 100 parts by weight of solvent. The recordable information layer is then metallized (i.e., to form a reflection layer), preferably under reduced pressure by sputtering or vapor deposition, and may then be provided with a protective coating (i.e., to form a protective layer) or with a further substrate or a covering layer. Multilayer arrangements having a semitransparent reflection layer are also possible.
Solvents or solvent mixtures for coating with the light-absorbing compounds of the formula (I) or their mixtures with additives and/or binders and other light-absorbing compounds are chosen on the one hand according to their solubility for the light-absorbing compound of the formula (I) and the other additives and on the other hand on the basis of a minimum effect on the substrate. Suitable solvents that have little effect on the substrate are, for example, alcohols, ethers, hydrocarbons, halogenated hydrocarbons, alkoxyalcohols, and ketones. Examples of such solvents are methanol, ethanol, propanol, 2,2,3,3-tetrafluoropropanol, butanol, diacetone alcohol, benzyl alcohol, tetrachloroethane, dichloro-methane, diethyl ether, dipropyl ether, dibutyl ether, methyl tert-butyl ether, methoxyethanol, ethoxyethanol, 1-methyl-2-propanol, methyl ethyl ketone, 4-hydroxy-4-methyl-2-pentanone, hexane, cyclohexane, ethylcyclohexane, octane, benzene, toluene, and xylene. Preferred solvents are hydro-carbons and alcohols since they have the slightest effect on the substrate.
Suitable additives for recordable information layer are stabilizers, wetting agents, binders, diluents, and sensitizers.